Ultrafiltration Combined with Coagulation/Flocculation/Sedimentation Using Moringa oleifera as Coagulant to Treat Dairy Industry Wastewater

Direct ultrafiltration and its combination with pretreatment by coagulation/flocculation/sedimentation using Moringa oleifera as coagulant to treat dairy industry wastewater were investigated. A single-channel tubular ceramic membrane with an average porosity of 0.1 μm was used at transmembrane pressures of 1, 2, and 3 bars, using the cross-flow filtration principle in a membrane filtration unit. Process efficiency was evaluated in terms of chemical oxygen demand (COD), apparent color, and turbidity removal, along with major requirements such as average permeate flux, percentage of fouling, and contribution of different resistances (resistances in series model) to the total resistance of the membrane. The highest removals for the evaluated parameters occurred in the combined coagulation/flocculation/sedimentation/ultrafiltration process. At a pressure of 2 bar, the removal of turbidity and apparent color was 99.9 % and that of COD was 98.5 %. For the combined process, the lowest percentage of fouling was 59.8 %, which occurred at 1 bar. The fraction of resistance due to fouling, which may indicate irreversible damage of the membrane, was lower in the process of coagulation/flocculation/sedimentation using M. oleifera as coagulant followed by ultrafiltration than in the process that treated dairy wastewater with direct ultrafiltration for all pressures.